Press working apparatus

ABSTRACT

A press working apparatus is provided that can prevent interference between the die and the punch and thus obtain a good sheared surface of a product. One embodiment is a press working apparatus comprising a lower mold frame on which a die is mounted, a sheet material being laid on the die; an upper mold frame movable toward and away from the lower mold frame; and a punch mounted on the upper mold frame for carrying out a predetermined press working on the sheet material laid on the die when the upper mold frame approaches proximately to the lower mold frame. Either the die or the punch can be freely displaced in its horizontal plane, and the press working apparatus further comprises a positioning apparatus for setting the relative position of the die and the punch.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based on and claims priority under 35 U.S.C. § 119 to Japanese Patent Application Serial No. 2006-303495, filed on Nov. 9, 2006, the entire contents of which are expressly incorporated by reference herein.

BACKGROUND

1. Field of the Invention

The present invention relates to a press working apparatus for press working a sheet material by moving a first mold frame toward and away from a second mold frame.

2. Description of the Related Art

As a conventional press working apparatus there is a punching apparatus having “compound dies” in which both outer and inner circumferential punching works are simultaneously performed. For example as disclosed in Japanese laid-open Patent Publication No. 2006-239711, such a punching apparatus comprises a lower mold frame on which a female shearing mold (die) is mounted, and an upper mold frame movable toward and away from the lower mold frame. The upper mold frame includes a male shearing mold (punch) for simultaneously performing both the outer and inner circumferential punching workings on a sheet material laid on the die when the upper mold frame approaches the lower mold frame.

Such a press working apparatus (punching apparatus) can prevent generation of shear drop and burring at a sheared surface of the product and can obtain a good sheared surface by setting a very small clearance between the female shearing mold and the male shearing mold. However, in the press working apparatus of the prior art, the die and the punch tend to interfere with each other when the upper mold frame approaches the lower mold frame due to errors in relative position between the die and the punch. Such problems with relative positioning can be caused for example, by rattle of structural elements of the apparatus.

Although it may be possible to set a relatively large clearance between the die and the punch, increased shear drop or burring would be caused in the sheared surface and thus a good sheared surface would likely not be formed. Such a phenomenon will be caused not only in punching work but in other press working such as deep drawing.

SUMMARY

Accordingly, there is a need in the art for a press working apparatus that can avoid interference between the die and the punch and thus obtain an improved sheared surface of a product.

In accordance with one embodiment, a press working apparatus is provided comprising a first mold frame on which a die is mounted, and a second mold frame on which a punch is mounted. The first and second mold frames are movable relative to one another in a direction of relative movement, and are further adapted to carry out press working on a sheet material arranged between the die and the punch. A positioning apparatus is configured to set the relative positions of the die and the punch. One of the die and the punch can be freely displaced in a plane generally perpendicular to the direction of relative movement.

In one such embodiment, the positioning apparatus comprises guide bars projected from one of the first and second mold frames toward the opposing mold frame, and guide bores are formed in the other of the first and second mold frames. The guide bores are configured to accept the guide bars therewithin when the first mold frame approaches the second mold frame.

In another embodiment, the first and second mold frames are disposed in a generally horizontal plane, and the first mold frame is disposed vertically below the second mold frame.

In yet another such embodiment, the die and the punch are respectively connected to the first mold frame and the second mold frame via pinned members secured on the associated mold frame. There is a clearance space between the pinned members and the associated die or punch. The die or the punch is able to freely displace in a generally horizontal plane by a distance determined by the clearance space.

In another embodiment, a retaining member is adapted to engage the horizontal and side surfaces of the associated die or the punch for preventing the associated die or the punch from slipping out of associated mold frame. In one such embodiment, the retaining member is generally L-shaped.

In still another embodiment, the punch is adapted to simultaneously perform both outer and inner circumferential punching works. In a yet further embodiment, the punch is adapted to contain scraps from the punching operation therewithin.

Since either the die or the punch can be freely displaced in its horizontal plane in some embodiments, it is possible to prevent the interference between the die and the punch and thus obtain a good sheared surface of a product.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic cross-section view of an embodiment of a punching apparatus showing a condition in which the upper mold frame is moved away from the lower mold frame;

FIG. 2 is a plan view of the lower mold frame of the punching apparatus of FIG. 1;

FIG. 3 is a schematic cross-section view of the punching apparatus of FIG. 1 showing a condition in which the upper mold frame approaches the lower mold frame;

FIG. 4 is a schematic explanatory view showing the outer and inner circumferential punching works performed by the punching apparatus of FIG. 1;

FIG. 5 is a schematic view of a connection between the die and the lower mold frame of the punching apparatus of FIG. 1;

FIG. 6 is a schematic view of a L-shaped member of the punching apparatus of FIG. 1; and

FIGS. 7 (a) and (b) are schematic views showing a centering operation carried out by the guide bar and the guide bore of the punching apparatus of FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Certain preferred embodiments of the present invention will be hereinafter described with reference to the drawings.

The press working apparatus of one embodiment of the present invention is for manufacturing annular products (e.g. clutch plates of a multiple disc clutch) by punching a metal sheet material “B” and is especially so-called “compound dies” in which both outer and inner circumferential punching works of the sheet material “B” are simultaneously performed. Such a punching apparatus comprises as shown in FIG. 1 a lower mold frame 1 on which a die 3 is mounted, an upper mold frame 2 on which a punch 5 is mounted, and a positioning apparatus that includes a guide bar 6 and a guide bore 7.

The illustrated sheet material “B” preferably is a belt shaped continuous material for example intermittently uncoiled by an uncoiler from a coiled material via a leveler feeder. In the illustrated embodiment, the sheet material “B” is fed toward the right in FIG. 1 and laid on the die 3 so as to be punched by the punch 5. That is, the sheet material “B” is adapted to be intermittently fed between the die 3 and the punch 5 so as to be punched to manufacture the annular sheet members.

The first or lower mold frame 1 preferably is secured on the press working apparatus and supports on its upper surface the die 3. The second or upper mold frame 2 is driven by a driving mechanism (not shown) so that it is moved toward and away from the lower mold frame 2. The punch 5 is mounted on the bottom surface of the upper mold frame 2 at a position oppositely corresponding to the die 3 on the lower mold frame 1. Four guide bores 7 (FIG. 2) are formed in the die 3 at predetermined positions and four guide bars 6 are arranged on the upper mold frame 2 so that each of them projects downward toward each of the guide bores 7. The sheet material “B” is intermittently fed with repeated stoppage of feeding when the upper mold frame 2 has approached proximately to the lower mold frame 1, and re-start of feeding when the upper mold frame 2 has moved away from the lower mold frame.

The illustrated die 3 has a central portion 3 a and an annular portion 3 b arranged vertically movable along the outer circumferential surface of the central portion 3 a. An annular opening 3 c is formed around the outer circumference of the annular portion 3 b. It should be noted that the die 3 including the central portion 3 a and the annular portion 3 b preferably can shift in the horizontal plane as a unit as will be hereinafter described in detail. The illustrated annular portion 3 b has outer and inner circumferential profiles corresponding to those of the product (see FIG. 2) and is movable relative to the central portion 3 a and the annular opening 3 c. The annular portion 3 b is returned upward to its original position by a knockout pin (not shown) abutting the bottom surface of the annular portion 3 b.

As shown in FIG. 5, the die 3 of the present embodiment is connected to the lower mold frame 1 via pinned members 8 and pretend by keeping a predetermined clearance “t” between the die 3 and each pinned member 8 so that the die 3 can freely displace in the horizontal plane by a distance determined by the clearance “t”. More particularly, the pinned members 8 of metal are mounted on the lower mold frame 1 so that they project from the lower mold frame 1 and are adapted to be inserted in holes “h” formed in the die 3. The radius of each hole “h” is set larger than that of each pinned member 8. Thus the die 3 can freely displace on the lower mold frame 1 by the distance “t” in the horizontal plane.

One or more retaining members 9 are arranged so that they surround the top and side surfaces of the die 3 or the punch 5 for preventing slipping out of the die 3 or the punch 5 respectively from the lower mold frame 1 or the upper mold frame 2. The illustrated retaining members 9 are L-shaped members 9 that extend along the top surface of the die 3 so that the L-shaped members 9 enable the horizontal displacement of the die 3 but prevent slipping out of the die 3 from the lower mold frame 1. As shown in FIG. 6 a predetermined clearance “u,” which preferably is larger than the clearance “t,” is provided between the die 3 and the L-shaped members 9 so as not to interrupt the horizontal displacement of the die 3.

The illustrated punch 5 has a punching edge 5 a for performing an outer circumferential punching work and a punching edge 5 b for performing an inner circumferential punching work. The punch 5 can simultaneously perform both outer and inner circumferential punching works and also can contain resulted scraps in a scrap containing space 5 c in a stacked manner. In the illustrated embodiment, a radially inwardly extending projection 5 d is formed on an opened edge leading to the scrap containing space 5 c.

As shown in FIG. 3 the tip end face of the punch 5 is designed so that it is opposite to the top end face of the annular portion 3 b of the die 3. The sheet material “B” is interposed therebetween when the upper mold frame 2 is lowered toward the lower mold frame 1. As the upper mold frame 2 descends further toward the lower mold frame 1, the annular portion 3 b of the die 3 is pushed downward together with the knockout pins (not shown) as shown in FIG. 4. During which the sheet material “B” is sheared and punched between the punching edge 5 a of the punch 5 and the circumferential edge of the opening 3 c as well as between the punching edge 5 b of the punch 5 and the outer circumferential edge of the central portion 3 a of the die 3.

That is, the outer and inner circumferential punching works can be simultaneously performed by shearing actions respectively between the punching edge 5 a of the punch 5 and the circumferential edge of the opening 3 c as well as between the punching edge 5 b of the punch 5 and the outer circumferential edge of the central portion 3 a of the die 3. Accordingly the annular products “W,” such as clutch plates of a multiple disc clutch, can be manufactured with high speed and high accuracy.

The projection 5 d helps prevent the scraps contained in the containing space 5 c from being dropped out therefrom when the upper mold frame 2 ascends relative to the lower mold frame 1.

As previously mentioned, in the illustrated embodiment, the guide bars 6 projected from the upper mold frame 2 are adapted to be inserted into the guide bores 7 formed in the die 3 as the upper mold frame 2 approaches toward the lower mold frame 1. As shown in FIG. 7( a) each guide bar 6 preferably has a tapered configuration 6 a at its tip end to effect a centering action relative to each guide bore 7.

According to this centering action, the die 3 is displaced in the horizontal plane to the predetermined condition relative to the punch 5 (i.e. a condition in which the clearance between the punching edge 5 a of the punch 5 and the circumferential edge of the opening 3 as well as the clearance between the punching edge 5 b of the punch 5 and outer circumferential edge of the central portion 3 a of the die 3 become the predetermined micro clearance). This condition helps to avoid interference between the punch and the die and thus to have a good sheared surface and good working accuracy of the product “W”. It should be noted that this can be achieved by a simple structure formed by the guide bars 6 and the guide bores 7.

In addition a pad 4 made of soft material is arranged around the punch 5. This pad 4 engages the sheet material “B” when the upper mold frame 2 approaches the lower mold frame 1. However since the pad 4 can move upward relative to the upper mold frame 2 when the upper mold frame 2 descends, the pad 4 does not interfere with the punching work. The annular portion 3 b of the die 3 is elevated beyond its initial position by knockout pins (not shown) so that easy taking out of the product “W” can be achieved.

As previously mentioned, scraps “B2” preferably are contained in the containing space 5 c of the punch 5 as shown in FIG. 4. In such a case it is preferable to previously form an aperture “Ba” in the sheet material “B” at a position corresponding to the scrap so as to direct radial stress generated in the contained scrap “B2” radially inward.

As previously mentioned the die 3 can be smoothly displaced in the horizontal plane by a simple structure by the distance “t” allowed by the clearance “t” of the pinned member 8.

Also the provision of the L-shaped retaining member 9 surrounding the circumference of the die 3 enables both prevention of slipping out of the die 3 from the lower mold frame 1 and free displacement of the die 3 along the horizontal plane by a simple structure. In addition as previously mentioned according to the present invention, since the outer and inner circumferential punching works can be simultaneously performed by the punch 5 and the die 3 and scraps can be contained in the punch 5, the annular products “W” can be manufactured with high speed and high accuracy.

Also according to the present embodiment, it is possible to avoid interference between the die 3 and the punch 5 since they are correctly positioned at a predetermined condition (micro clearance condition) by the guide bars 6 and the guide bores 7.

The inventive principles discussed herein can be applied to various kinds of press working apparatus if they have structures in which the relative position of the die and the punch can be corrected to a predetermined condition.

Principles of the present invention have been described with reference to an example preferred embodiment. Obviously, modifications and alternations will occur to those of ordinary skill in the art upon reading and understanding the preceding detailed description. For example, the guide bars may be arranged on the lower mold frame and the guide bores may be arranged on the upper mold frame. In another way the guide bars and the guide bores may be arranged on the punch itself or its related elements and on the die itself or its related elements so that either one of the punch or the die can be shifted to a predetermined correct position. Further, although the example press apparatus is configured with an upper and lower mold frame, other configurations, such as side-by-side mold frames, can be employed. Also, dies and punches having various configurations can be appropriately used.

Although this invention has been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. In addition, while a number of variations of the invention have been shown and described in detail, other modifications, which are within the scope of this invention, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or subcombinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the invention. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed invention. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow. 

1. A press working apparatus comprising a first mold frame on which a die is mounted, a second mold frame on which a punch is mounted, the first and second mold frames being movable relative to one another in a direction of relative movement, the first and second mold frames further being adapted to carry out press working on a sheet material arranged between the die and the punch, and a positioning apparatus configured to set the relative positions of the die and the punch, wherein one of the die and the punch can be freely displaced in a plane generally perpendicular to the direction of relative movement.
 2. The press working apparatus of claim 1, wherein the positioning apparatus comprises guide bars projected from one of the first and second mold frames toward the opposing mold frame, and guide bores formed in the other of the first and second mold frames, the guide bores configured to accept the guide bars therewithin when the first mold frame approaches the second mold frame.
 3. The press working apparatus of claim 1, wherein the first and second mold frames are disposed in a generally horizontal plane, and the first mold frame is disposed vertically below the second mold frame.
 4. The press working apparatus of claim 1, wherein the die and the punch are respectively connected to the first mold frame and the second mold frame via pinned members secured on the associated mold frame, wherein there is a clearance space between the pinned members and the associated die or punch, and wherein the die or the punch is able to freely displace in a generally horizontal plane by a distance determined by the clearance space.
 5. The press working apparatus of claim 4 further comprising a retaining member adapted to engage the horizontal and side surfaces of the associated die or the punch for preventing the associated die or the punch from slipping out of associated mold frame.
 6. The press working apparatus of claim 5, wherein the retaining member is generally L-shaped.
 7. The press working apparatus of claim 5, wherein the punch is adapted to simultaneously perform both outer and inner circumferential punching works.
 8. The press working apparatus of claim 7, wherein the punch is adapted to contain scraps from the punching operation therewithin.
 9. The press working apparatus of claim 1, wherein the punch is adapted to simultaneously perform both outer and inner circumferential punching works.
 10. The press working apparatus of claim 9, wherein the punch is adapted to contain scraps from the punching operation therewithin. 